1. Field of the Invention
This invention relates to an apparatus and method for non-invasively generating a fibrous matrix layer of tissue beneath the skin, and more particularly, preventing subdermal tissue from entering or protruding into to the dermis for treating patients having cellulite, or for the purpose of causing the contraction of laxed or wrinkled tissues below the surface of the epidermis.
2. Prior Art
The distribution of adipose tissue throughout the body is not uniform. In certain portions of the body it is present in great abundance such as in the subcutaneous tissue. A distinction must be made between fat and adipose tissue; the latter being a distinct tissue, the former an oily substance. Adipose tissue consists of small vesicles referred to hereinafter as xe2x80x9cfat cellsxe2x80x9d lodged within the matrix of areolar connective tissue. Fat cells vary greatly in size; having an approximate diameter of about 0.05 mm. They are formed of a delicate protoplasmic membrane filled with the oily substance which is liquid during life but solidifies after death. These fat cells are contained in discrete clusters in the areolae of fine connective tissue.
Areolar tissue is a form of connective tissue wherein the investing connective tissue matrix is separated into areolae or spaces which open into one another and are easily permeated by fluids. Areolar tissue binds different parts of the body together. The elasticity of areolar tissue and the permeability of its areolae allows the various parts of the body to move relative to one another. Most particularly, areolar connective tissue is found beneath the skin in a continuous layer all over the body, connecting the skin (dermis) to subjacent tissues. In many parts the areolae are occupied by fat cells; the matrix and fat cells constituting adipose tissue which is referred to alternatively herein as xe2x80x9cdepot fatxe2x80x9d.
It is now well established that the phenomena of cellulite is due to a protrusion of pockets of depot fat from subcutaneous tissue through an elastic layer of connective tissue overlying the depot fat into the dermis. Patients having cellulite appear to exhibit a deficiency in the fibrous layer at the interface between the dermis and the subcutaneous tissue. This deficiency enables depot fat below the interface to protrude up through the fibrous layer and into the dermis thereby causing irregular elevations and depressions of the dermis characterized by a xe2x80x9cdimpledxe2x80x9d appearance. This condition, and the underlying causes, is discussed by Rosenbaum et al. in Plastic and Reconstructive Surgery, Vol. 104. No. 7, Pages 1934-1939, June, 1998.
Ultrasonic, microwave, nuclear magnetic resonance and other radiative techniques have been employed to provide images of organs within the body and/or to effect treatment of subdermal tissue without necessitating traumatic incision of the overlying tissue. The purpose of such radiative application is directed toward destruction of target cells in a particular target area beneath the skin or to view organs, tumors or other structures for diagnostic purposes. Therapeutic applications include the cauterization of blood vessels via hyperthermia for traumatic injury resulting in bleeding, as occurs, for example, in trauma to the liver. In addition, such radiative treatment may be employed for diagnosing medical conditions, treating prostate hypertrophy, non-invasive lipectomy or for the treatment of brain cancer. Various devices have been designed and disclosed for performing these procedures. Exemplary of such devices is U.S. Pat. No. 5,769,790 to Watkins, et al.; U.S. Pat. No. 5,143,063 to Fellner and U.S. Pat. No. 5,507,790 to Weis. There appears to be no reference in the literature for using radiative energy sources for the purpose of non-invasively forming and/or reinforcing a connective tissue layer beneath the skin of a patient.
Knowlton, in U.S. Pat. No. 5,755,753, discloses a method for tightening skin. The method comprises providing a membrane containing a cooling fluid in combination with a thermal energy source. A reverse thermal gradient is created which cools the surface of the skin while heating underlying collagen-containing layers of tissue. The skin and underlying collagen-containing tissue are then heated without substantially modifying the melanocytes and other epithelial cells in the epidermis. The result is a contraction of collagen tissue and a tightening of the skin. Radiant energy is applied to a variety of different skin layers including the papillary dermis layer, the reticular dermis layer, and even to a subcutaneous layer and to underlying soft tissue. A suitable energy source is one or more RF electrodes. Electrolytic solution contained within the membrane transfers RF energy from the RF electrodes to the underlying collagen tissue. The cooling fluid creates a reverse thermal gradient between the epidermis and the underlying desired layers of about 30 degrees to about 80 degrees C. The creation of the reverse thermal gradient provides for the controlled contraction of collagen tissue, e.g., partial denaturization of the collagen molecules that results in a shrinkage of the collagen tissue, which then extends to a shrinkage of the skin. Creation of the reverse thermal gradient is different from other methods of collagen contraction which typically employ a thermal gradient that has a higher temperature at the surface and decreases with the depth of penetration. Thus, Knowlton""s device and method for causing shrinkage of the skin requires cooling the epidermis while heating collagen in the underlying tissue via radiant means such as an RF field.
Knowlton ""753 addresses the problem of tightening the skin by increasing cross-linking in collagen in a selected target layer of tissue beneath the skin. That is, the method of Knowlton does not stimulate production of collagen by cells within the target tissue. The method, instead, relies upon increasing the cross linking between amino acids in adjacent collagen fibrils. While Knowlton ""753 does not present data specifying a temperature threshold above which the objectives of the method are achieved, the thermoregulating ability of the body renders it difficult, if not impossible, to raise the temperature of a layer of tissue underlying the (cooled) epidermis to a point where denaturation of collagen will occur by employing non-invasive hyperthermia means. The present invention provides a method for stimulating the production of additional collagen in a preselected target area thereby increasing the collagen content in the tissue.
It is a first object of this invention to provide an apparatus creating controlled tissue injury and repair for structurally reinforcing one or more layers of connective tissue beneath the skin of a patient.
It is another object of this invention to create or reinforce a layer of connective tissue at the interface between the dermis and the subcutaneous tissue of a patient by non-invasive means.
It is yet another object of this invention to provide a method for enhancing the integrity of a connective tissue layer beneath the dermis to prevent lobules comprising adipose tissue from protruding into the layer of skin comprising the dermis.
It is a further object of this invention to provide a means for strengthening the fibrous layer of tissue at the interface between the dermis and the subcutaneous tissue to reduce or prevent cellulite.
The features of the invention believed to be novel are set forth with particularity in the appended claims. However, the invention itself, both as to organization and method of operation together with further objects and advantages thereof may best be understood by reference to the following description taken in conjunction with the accompanying drawings in which: